JPS61225696A - Turbine controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a turbine control AT+ device, and relates to a turbine control device suitable for application to a boiling water nuclear power plant (referred to as a BWR power plant). It is.

[Background of the invention]

In the BWR power generation plan), steam generated in the reactor pressure vessel is sent to the turbine through the main steam pipe. Steam exhausted from the turbine is condensed in a condenser.

The main steam pipe is connected to the condenser via bypass piping that bypasses the turbine. A turbine bypass valve is provided in the bypass piping. A turbine steam control valve is provided in the main steam pipe downstream of the branch point between the main steam pipe and the bypass pipe. A generator is coupled to the turbine.

When the steam generated in the reactor pressure vessel is supplied to the turbine, the turbine rotates together with the generator.

The flow rate of turbine steam supplied to the turbine through the main steam pipe is regulated by controlling the opening degree of the turbine steam control valve to keep the steam pressure at the turbine inlet constant. This control is performed by the main steam pressure adjustment circuit. For example, if the reactor power is increased (or decreased) by changing the core flow rate by controlling the recirculation flow rate and the steam pressure rises (or falls) above the set point, the turbine steam control valve is opened and the reactor power is increased (or decreased). or closed) increases the turbine output to C or decreases it to try to keep the steam pressure constant. If the steam pressure rises further and cannot be suppressed even if the turbine steam control valve is opened, the turbine bypass valve is opened to dump the steam directly to the condenser, thereby suppressing the rise in steam pressure. I have to.

As described above, during normal operation, the opening degree of the turbine steam control valve is controlled by commands from the main steam pressure regulation circuit. However, if the rotation speed of the generator exceeds the set point due to a sudden load reduction on the power grid side, etc., the rotation speed of the generator is changed based on the output signal from the turbine speed control circuit that inputs the detected rotation speed of the generator. (priority is given to the output signal of the main steam pressure regulating circuit), the opening degree of the turbine steam control valve is reduced to prevent acceleration of the turbine.

However, commands from the turbine speed control circuit close the turbine steam control valve only when the turbine speed exceeds a set value.

An example of such a turbine control device is disclosed in Japanese Patent Application Laid-open No. 54
There is one shown in Japanese Patent No.-144587.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a turbine control device that can stably control the fast cycle response required for the governor free function without scramming the reactor.

[Summary of the invention]

The features of the present invention include means for obtaining a control valve opening correction signal based on the output signals of a turbine rotation speed detector and a neutron detector, and means for correcting a control valve control signal using a control valve opening correction signal. The present invention also includes means for controlling the opening degree of the steam regulating valve based on the corrected regulating valve control signal outputted from the correcting means.

The present invention was developed based on a detailed study of the operation of a conventional turbine control device for a BWR power plant, and based on the study results.

The conventional turbine control device described above performs the following control when the system load on the power system side decreases. An increase in power system frequency due to a decrease in system load is detected as turbine rotation speed.

The detected turbine rotation speed is input to a turbine speed control circuit. However, when the system load decreases, the input to the turbine speed control circuit becomes less than 0.54, and the output 8 of the turbine speed control circuit also becomes less than 110%. At the same time, the difference between the output signal SL of the turbine speed control circuit and the output signal P1 of the main steam pressure regulation circuit, that is, (SI
P+) also becomes smaller. However, if the required reduction in system load for a BWR power plant is less than 10%,
If the rate of change is slower than the follow-up rate of the reactor output even if the rate exceeds 10, the output signal S1 becomes the output signal P.
It never becomes smaller than l, and the opening degree of the turbine steam control valve is still controlled by the command from the main steam pressure control circuit.

However, the reduced output signal S1 is compared with a bias of 10 and is further applied to the output signal P1 as a negative load deviation signal to the recirculation system main controller and set pressure regulating circuit. After the recirculation system main controller receives the negative request signal, the recirculation flow rate control device 20 lowers the fluid coupling output shaft rotation speed of the MG set, that is, the output frequency of the alternator of the MG set, and controls the recirculation pump. The reactor output is reduced by lowering the rotation speed of the reactor.

As a result, the steam pressure falls below the rated value, a negative input signal is given to the main steam pressure regulating circuit, and the output signal P+ decreases. In this way, the output signal Pt becomes smaller than the output signal SR, and the opening degree of the turbine steam control valve is closed until the difference between them becomes zero, reducing the turbine output. The negative load request signal is also led to the set pressure regulation circuit at the same time, which applies a negative input command to the main steam pressure regulation circuit, giving the same effect as if the steam pressure had decreased without waiting for the reactor power to decrease. This improves the initial response characteristics to load requests.

An example of a response using such a control system is shown in FIG.

In this control method, the recirculation yI is first adjusted according to the load deviation signal.
Since the reactor core flow rate is changed by changing the k flow rate and thereby the reactor output is changed to make the load deviation zero, there is a problem that it is not possible to follow load fluctuations in a fast cycle.

Normally, the governor-free function is required to follow load fluctuations with a period of several seconds and a width of 1 to 2 seconds, and this control method does not meet this requirement and has excellent responsiveness. A control method is required.

The present invention, which was developed based on the results of such studies, will now be described in detail.

[Embodiments of the invention]

A turbine control device that is a preferred embodiment of the present invention applied to a BWR power plant will be explained based on FIGS. 1 and 2.

Before explaining the turbine control device, an overview of the Jll'R power plant will be explained based on FIG. 2.

When the recirculation pump 3 installed in the recirculation system piping 52 connected to the reactor pressure vessel 1 rotates, the reactor pressure vessel 1
The cooling water inside is ejected into the jet pump 4 through the recirculation system piping 52. This allows cooling water to flow to the core 5.
Supplied within 0.

The recirculation pump 30 rotation speed is controlled by a recirculation flow control device 2 having an MG set. Recirculation pump 3
Changes in the rotational speed of the recirculation system lead to changes in the flow rate of cooling water flowing through the recirculation system piping 5, and further affect changes in the core flow rate supplied to the reactor core 50 through the jet pumps 4. When the core flow rate changes, the reactor power changes in a BWR. Steam generated in the reactor core 50 within the reactor pressure vessel 1 is guided to the turbine 8 through the main steam pipe 6.

The reactor pressure vessel 1 of the BWR is a steam generator.

Steam discharged from the turbine 8 by rotating the turbine 8 is condensed in the condenser 16 . One end of the bypass pipe 51 is connected to the main steam pipe 6, and the other end of the bypass pipe 51 is connected to the condenser 16. Main steam pipe 6 and bypass pipe 5
A turbine steam control valve 7 is provided in the main steam pipe 6 downstream of the branch point with the main steam pipe 1 . A turbine bypass valve 15 is installed in the bypass piping 51. The generator 9 is connected to the turbine 8 and rotates as the turbine 8 rotates. The power generated by the generator 9 is transmitted to the power grid 10. 60 is a control rod that is inserted into the reactor core 50 to adjust the reactor output, and 61 is a control rod drive device that drives the control rod 60.

The turbine control device of this embodiment includes a low value selection circuit 5, a main steam pressure regulation circuit 12, a turbine speed control device 19, and a governor free control device 36. The governor free control device 36 is a regulating valve opening pressure regulating device. Note that the turbine control device includes a main steam pressure detector 11. which is attached to the main steam pipe 6 as a detector. It has a rotation speed detector 17 that detects the rotation speed of the turbine 80, a neutron detector 30 installed in the reactor core 50, and a core flow rate detector 31. In FIG. 2, 14 is a steam pressure setting device, 18 is a turbine rotation speed setting device, 20 is a switch controller, 21 is a bias, 32 is a reactor power calculation section, and 53 is a 7-channel valve of the turbine steam control valve 7. , 54 is the turbine bypass valve 1
5 and 7, 55 to 57 are adders, and 58 is a switch. The adder 56 is a correction circuit that corrects the adjustment valve opening control signal as described later.

The governor free control device 36 receives output signals from the rotation speed detector 11 , the turbine rotation speed setting device 18 , the neutron detector 30 , the core flow rate detector 31 , and the thermal output calculation unit 32 . The governor free control device 36 has a governor free control section 25, a fluctuation width limiting section 28, and a neutron flux setting device 29, as shown in FIG. 26 and 27 are adders.

The governor free control unit 25 is a control valve opening adjustment value calculation unit. The variation range limiter 28 is a circuit that corrects the variation range of the control valve opening adjustment signal. The governor free control unit 25 is
As shown in FIG. 3, it consists of a regulating valve adjustment rate section 24A and a filter section 24B. As shown in FIG. 4, the variation width limiting section 28 includes function generators 41 and 44, an adjustment signal variation width correction circuit 42, and a low value selection circuit 43. The neutron flux setting device 29 has a neutron flux manual setting device 38, an automatic neutron flux setting device 39, and a changeover switch 40, as shown in FIG.

The operation of the turbine control device of this embodiment will be described below.

The steam pressure of the main steam pipe 6 detected by the main steam pressure detector 11 and the steam pressure set value that is the output of the steam pressure setting device 14 are input to an adder 55 .

Adder 55 outputs a deviation signal between the two input signals.

This deviation signal is input to the main steam pressure adjustment circuit 12, and the main steam pressure adjustment circuit 12 outputs an output signal P1 based on the input deviation signal. The turbine rotation speed detected by the rotation speed detector 17 and the turbine rotation speed setting value which is the output of the turbine rotation speed setting device 18 are transmitted to the turbine speed control device 1.
9 is input. The turbine speed control device 19 outputs an output signal Ss based on the above two input signals.

The output signals PK and St are input to the low value selection circuit 5. The low value selection circuit 5 selects two input signals Pt and Sl.
The signal of the lowest one shift is selected and output. It is equal to the low value signal of the output signal KFi, output signal PK and Sl of the low value selection circuit 5.

When the load on the power system 10 suddenly decreases, the output signal Ss of the turbine speed control device 19 changes to the main steam pressure regulation circuit 12.
output signal P1.

Therefore, the output signal of the low value selection circuit 5 is the output signal St.
is equal to The switch controller O-220 compares the output signal to the output signal S1 and opens the switch 58 if their values are equal. Therefore, the output signal of the governor free controller is not input to the adder 56. Therefore, the output signal of the low value selection circuit 5 is 1, that is, the output signal Sl is input to the actuator 53. The actuator 53 reduces the opening degree of the turbine steam control valve 53 based on the output signal S1, thereby reducing the amount of steam supplied to the turbine 8. This can prevent overspeeding of the turbine 8 when the load on the power system 10 suddenly decreases. The output signal S1 output from the low value selection circuit 5 is input to the adder 57. Adder 57
inputs the bias signal outputted from the bias 21 and the output signals P1 and Sl, and inputs their deviation signal to the actuator 54. When the level of the output signal S1 is extremely low, it is necessary to significantly reduce the opening degree of the turbine steam control valve 53, and in order to prevent the main steam pressure from increasing, the turbine Bypass valve 15 is opened.

Except when the load on the power system 10 suddenly decreases as described above, the low value selection circuit 5 outputs the output signal PK as an adjustment valve opening control signal. The switch controller 20 is
Since the input output signal P1 and output signal S1 have different values, the switch 58 is closed. Therefore, the adder 56 outputs the output signal P1 of the low value selection circuit 5 and the governor free control device 3.
The control valve opening correction signal L1, which is the output of step 6, is added.

That is, the adder 56 corrects the output signal P1, which is the adjustment valve opening control signal, using the adjustment valve opening correction signal L1. In this way, the output signal P1 is corrected by the output signal L1. Output signal of adder 56 (P1+Ll)
is input to the actuator 53. The actuator 53 adjusts the opening degree of the turbine steam control valve 7 based on the output signal (PI +I, l) to try to keep the main steam pressure constant. If the main steam pressure rises further and the rise in main steam pressure cannot be suppressed even if the opening degree of the turbine steam control valve 7 is increased, the turbine bypass valve 15 opens.

Next, the first section regarding the operation of the governor free control device 1i36 will be described.
This will be explained in detail based on the drawings and FIGS. 3 and 4.

The turbine rotation speed detected by the rotation speed detector 17 and the turbine rotation speed setting value which is the output of the turbine rotation speed setting device 18 are input to the adder 26 . Adder 26 adds these signals to obtain turbine rotation speed deviation signal L2. The governor free control unit 25 outputs a turbine rotation speed deviation signal L2.
is converted into an adjustment valve opening degree deviation signal by the adjustment valve adjustment rate section 24AK, and a high frequency component of the adjustment valve opening degree control signal that cannot be followed by the turbine steam adjustment valve 7 is removed by the filter section (-th order lag element) 24B. In this way, the governor 7 re-controls the controller 2.
The adjustment valve opening adjustment value obtained in step 5 is input to the fluctuation range limiting section 28, which is a fluctuation range correction circuit, as the adjustment valve opening adjustment signal L3.

The neutron flux setting device 29 selects the output signal of the neutron flux manual setting device 38' or the neutron flux automatic setting device 39 using the changeover switch 40 and outputs it as a neutron flux setting value signal L4. The neutron flux automatic setting device 39 includes a core flow rate detector 3.
The core flow rate name X detected in step 1 is input.

The adder 27 obtains a deviation signal L5 between the neutron flux setting value signal L4 and the neutron flux signal measured by the neutron detector 30. The deviation signal Ls is input to the fluctuation width limiting section 28. The reactor power calculation unit 32 calculates the reactor power based on the neutron flux signal measured by the neutron detector 30. This reactor output is also input to the fluctuation range limiter 28 together with the measured neutron flux signal.

The function generator 41 of the fluctuation width limiter 28 obtains a fluctuation tolerance width signal indicating the correction ratio based on the deviation signal Ls between the set value of the neutron flux and the measured value. The function generator 41 outputs a three-step variation tolerance signal (correction ratio signal) as shown in FIG. 6 for the magnitude of the input deviation signal L5. In other words, when the deviation signal L5 is within ±5% (first region), the variation tolerance signal that limits the variation tolerance range to ±3% is set to a range where the deviation signal L5 is ±5% or more and within ±15%. In the case of (region), the neutron flux fluctuation exceeds the noise, so in this case, the permissible fluctuation range signal that limits the permissible fluctuation range to ±1 is
If the deviation signal Ls is in the third region exceeding the ±15 factor, the permissible fluctuation width is limited to iQ4. 6 permissible fluctuation width signal? Output.

The function generator 44 of the fluctuation range limiter 28 calculates the core flow rate measured by the core flow rate detector 31 and the reactor power calculation unit 32.
Input the reactor output obtained in , and calculate the correction ratio, i.e., the correction ratio, based on these values. That is, the function generator 44 divides the operation range of the BW reactor into three regions I-III as shown in FIG. ±
A permissible fluctuation range signal is output that limits the permissible fluctuation range to 2°, and a permissible fluctuation range signal that limits the permissible fluctuation range to ±3° for region H is output. Region (2) is a reactor power region between region (2) and region (2).

The low value selection circuit 43 selects an output signal indicating a low value from among the permissible variation width signals output from the function generators 41 and 44 and outputs the selected output signal to the adjustment signal variation width correction circuit 42 . The adjustment signal fluctuation width correction circuit 42 corrects the fluctuation range of the input adjustment valve opening adjustment signal L3 based on the input fluctuation tolerance width signal, and brings the fluctuation width of the adjustment valve opening adjustment signal L3 within the fluctuation tolerance range. The controlled adjustment valve opening correction signal L1 is output to the adder 56.

The fluctuation range limiter 28 can variably change the permissible fluctuation range according to the deviation signal Ls between the neutron flux setting value obtained by the neutron flux setting device 29 and the neutron flux measurement value measured by the neutron detector 30. That is, when the deviation signal Ls is large, the permissible fluctuation range is made small to prevent the neutron flux fluctuation from becoming even larger, and when the deviation signal Ls is small, the maximum permissible fluctuation range is set to increase the load following ability.

Further, the fluctuation range control unit is capable of changing the permissible fluctuation range according to the operating point by inputting the core flow rate and the reactor output. This is because the permissible range of neutron flux fluctuation differs based on the operating point, and at high reactor power near the rod block line or low reactor power near the jet pump cavitation line, neutron This is because the permissible variation range needs to be kept sufficiently small.

The adder 56 corrects the adjuster valve opening control signal K (output signal Ps) using the adjuster valve opening correction signal L1, and 1 is input to the actuator 53 as the adjuster valve opening control signal. The actuator 53 controls the opening degree of the turbine steam regulating valve 7 based on the regulating valve opening control signal 1 to perform load following (governor free).

The turbine control device of this embodiment prevents scrams caused by high neutrons and improves quick response by suppressing neutron flux fluctuations, which were a problem when directly controlling the turbine steam control valve 7 in the BW power generation plan. Excellent governor-free operation is possible.

The specific responses of the turbine control device of this embodiment to various operating states of the BWR power plant C1 except for the state in which the load on the power system 10 suddenly decreases will be described below.

Here, the behavior of the BWR power plant when the regulator valve opening control signal K (output signal P1) is not corrected by the regulator valve opening correction signal L1 is shown in FIG. 8rA).

Shown in (B) and (C). As is clear from Figure 8 (CI), the fluctuations in neutron flux can reach about ±20%, which far exceeds the normal fluctuation range.

For this reason, the core state becomes unstable and there is a risk that the reactor will reach a high neutron flux scram when the reactor power is high.

The turbine control device of this embodiment can avoid such problems. Its function will be explained for various operating conditions.

(1) Variation range limited by neutron flux Neutron flux setting value L4 output from neutron flux setting device 29
As described above, the permissible fluctuation range is limited in stages by the deviation signal Ls between the neutron flux measurement value and the neutron flux measurement value output from the neutron detector 30. The behavior of the BWR power plant during governor free control in each operation mode is shown below.

(a) During pace load operation When the BWR power plant performs base load operation, the measured neutron flux value fluctuates by a noise amount with respect to a constant value. In this case, changeover switch 40 is set to terminal 4.
0A and set the neutron flux setting value using the neutron flux manual setting device 38. Then, the difference between this set value and the measured neutron flux value (deviation signal Ls) is determined, and the permissible fluctuation range is limited by the deviation signal L5. As described above, the permissible variation range is limited to one of the three stages by the function generator 41, so that governor free is temporarily stopped and the neutron flux is stabilized. Since the neutron flux is stabilized in a few seconds, governor-free control can be resumed immediately.

Mountain) During power change operation When governor free control is superimposed during daily load adjustment operation and AFc operation in which the reactor output direction is changed by changing the core flow rate, the neutron flux setting changes because the neutron flux itself changes. It is necessary to change the neutron flux set value, which is the output of the device 29, according to the operation. In this case, the neutron flux fluctuation is calculated from the core flow rate and the neutron flux setting value is changed in accordance with the output change. As a function for deriving the neutron flux from the core flow rate, the following equation can be considered, where the core flow rate is x1 and the neutron flux is ψ.

ψ=aX+b+CX' (x' is the time derivative of core flow rate) However, x/ is the time differential of the core flow rate.

This calculation is performed by the neutron flux automatic setting device 3 of the neutron flux setting device 29.
It will be held at 9. After the automatic neutron flux setting device 39 outputs the neutron flux setting value L4, the allowable fluctuation range is limited by the above-mentioned (
Same as in item a).

Selection of the manual neutron flux setting device 38 and the automatic neutron flux setting device 39 in the operation modes (a) and (b) shown above is performed by the changeover switch 39.

(2) Limitation of permissible fluctuation range based on operating region The current operating region is determined based on the core flow rate and reactor output, and the permissible fluctuation range C determined in advance by the operating region is limited as shown in FIG. 7.1. Such a limit on the permissible variation range is performed by the function generator 44 described above.

The fluctuation range limiting section 28 inputs the permissible fluctuation width signals outputted from the function generators 41 and 44 to the low value selection circuit 43, and limits the permissible fluctuation range using the lower value (change width limiter 42). do.

This enables optimal governor-free control depending on the operating range and neutron flux fluctuations.

According to this embodiment, even when governor-free control is performed in which the turbine steam control valve 7 is directly controlled using the turbine rotational speed deviation in a BWR power plant, fluctuations in neutron flux can be minimized and sufficient load tracking can be achieved. It is possible to acquire abilities.

The reactor power is adjusted as described above by operating the recirculation flow control device 2 or the control rod drive device 61. In this embodiment, the reactor output can be controlled without considering the turbine side, and the state quantity of the reactor power plant based on the reactor output control is input to the governor-free control device 36 for governor-free operation. can be carried out. Therefore, the structure of the turbine control device is extremely simplified.

[Effects of the Invention] According to the present invention, it is possible to directly control the control valve while suppressing fluctuations in neutron flux in response to rapid load fluctuations, so that load following ability can be improved.

[Brief explanation of the drawing]

1 is a detailed circuit diagram of the governor-free control device shown in FIG. 2, FIG. 2 is a configuration diagram of a turbine control device that is a preferred embodiment of the present invention, and FIG. 3 is a detailed circuit diagram of the governor-free control device shown in FIG. 1. A detailed structural diagram of the control section, FIG. 4 is a detailed structural diagram of the fluctuation range limiter shown in FIG. 1, FIG. 5 is a detailed structural diagram of the neutron flux setting device shown in FIG. 1, and FIG. An explanatory diagram showing the permissible fluctuation range of the generator 41, FIG. 7 is an explanatory diagram showing the permissible fluctuation range of the function generator 44 in FIG. 4, and FIG. 8 is a nuclear power plant without the fluctuation range limiter 28. FIG. 9 is an explanatory diagram showing an example of the response of a conventional nuclear reactor power plant. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Recirculation flow rate control device, 3... Recirculation pump, 5... Low value selection circuit, 6...
...Main steam pipe, 7...Turbine steam control valve, 8...
Turbine, 9... Generator, 10... Power system, 11
... Main steam pressure detector, 12... Main steam pressure adjustment circuit, 15... Turbine bypass valve, 17... Rotation speed detector, 19... Turbine speed control device, 25...
Governor free control section, 28... Fluctuation range limiting section, 29.
...Neutron flux setting device, 30...Neutron detector, 31.
... Core flow rate detector, 32 ... Reactor power calculation section 3rd 6th eye 0 20 40 60 B□
to. seconds・(flow rate ('/)

Claims (1)

[Claims] 1. A steam control valve that adjusts the amount of steam supplied to the steam generated in the reactor vessel, a steam pressure detector that detects the pressure of the steam, and a rotation speed detector that detects the rotation speed of the turbine;
a neutron detector installed in the reactor vessel; a steam pressure adjustment means for inputting an output signal of the steam pressure detector and outputting a control valve control signal; means for obtaining an adjustment valve opening correction signal based on an output signal; means for correcting the adjustment valve control signal using the adjustment valve opening correction signal; and a corrected adjustment valve control signal output from the correction means. A turbine control device comprising means for controlling the opening degree of the steam control valve based on.